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(https://github.com/esp8266/Arduino/
releases/tag/3.0.0).
The quickest fix will be to change
the installed version of the board profile from the Boards Manager (there is
a drop-down to change the version).
We don’t have a record of the version
used for the original project, but it was
likely one of the later 2.x.x versions.
We suggest you try 2.7.4.
There were similar problems with
the Clayton’s GPS Time Source project
and version 2.7.4 worked in that case.
Wideband Differential
Probe output is too high
I’ve finally got around to building the Wideband Active Differential Probe (from the September 2014
issue; siliconchip.au/Article/7995). I
ordered the parts in 2015, lost them,
then finally ordered them again a couple of months ago...
siliconchip.com.au
I realise that this is an old project.
However, I wondered if you might
have any troubleshooting information
available based on any questions at the
time. I’ve looked in my old magazines
for the couple of months after in case
there was anything there, but didn’t
find anything.
My problem is that when feeding
in a 2V peak-to-peak square wave at
around 200kHz, the voltages displayed
on the oscilloscope are either 3.32V
peak-to-peak at ×1 or an overshooting
3.6V peak-to-peak (3.2V if I ignore the
overshoots) at ×10. The overshooting
looks much like the shape of needing
to calibrate a probe.
The connection to the oscilloscope
is an SMA-to-BNC coaxial cable and
I’m feeding the probe’s inputs from the
50W output of a signal generator via a
BNC to crocodile clip coaxial cable.
I’ve measured the output of the signal
generator using its 600W output direct
Australia's electronics magazine
to the scope with a BNC-BNC coaxial
cable and this matches the 2V peak-topeak the generator claims to put out.
Any troubleshooting thoughts, hints
or pointers would be much appreciated. (J. B., Little River, New Zealand)
● The Wideband Active Differential Probe is designed to be used with
a 50W cable to the oscilloscope and
with 50W termination. Without this,
the displayed levels will be incorrect.
Many oscilloscopes have a 50W termination option for each input. Make
sure you’ve enabled it for the one the
Probe is connected to.
If you are using this 50W termination, perhaps the gain of the differential amplifier is not correct. Check the
values of the 1kW and 1.3kW resistors
that set the gains of IC1 and IC2. Also
check that the three 3MW resistors in
series at the input and the 1MW shunt
resistors at the gates of Q1 and Q2 are
correct.
April 2025 103
